Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Pentax / Samsung dSLR, K Mount Mirrorless

Reply
 
Thread Tools Search this Thread
Old Apr 12, 2009, 9:13 PM   #21
Senior Member
 
beachboy2's Avatar
 
Join Date: Aug 2005
Location: Perth, Western Australia
Posts: 517
Default

Hi Patty, lots of good advice above from Penolta. I might suggest you try your testing at a fixed aperture, say F8 at this is often more or less the optimum for lenses. Sometimes for perfect optics wide open is best (theoretically it should be). Your photos above include apertures of F22 etc. Diffraction means that images will be less sharp when the lens is stopped down too much. Otherwise we would all use pin hole cameras! Also your shutter speeds are way too slow for lens testing. You need a bright sunny day I think to help with testing. What about using TAV mode with F8 and say 1/500sec exposure. Remember to set focussing to spot mode so you know what should be in focus. Select a subject with lots of contrast. No charming foggy valleys or surreal misty mornings.

Good luck

bb2

PS I recently bought a second hand prime lens. Got home, took some photos, they were awful! Perservered, got use to this manual lens and have now decided it is possibly my best lens!

beachboy2 is offline   Reply With Quote
Old Apr 13, 2009, 6:31 AM   #22
Senior Member
 
nhmom's Avatar
 
Join Date: Jun 2006
Location: Southern New Hampshire
Posts: 5,202
Default

Thanks for the extra input, bb2. I was trying at different apertures. Largest, F16 and smallest at both long and short distances. Hadn't noticed the ones I'd posted were at smallest opening. Needless to say, results were always the same.

I had been doing AV mode, but will switch to TAV and your settings. The first day I had the camera and noticed it was outdoors on a sunny day at the zoo. I would love it if this lens has no problems and it's me. Other than this problem I'm having, it's a great lens.

Btw, has anyone heard about his lens being discontinued. It's still up on the Pentax site. But, I've found a post in Rice High's blog and on the Pentax forums about it being discontinued. Not that it makes a difference. I'd still buy the lens. I just think it's strange with it being so new and all.

Patty
nhmom is offline   Reply With Quote
Old Apr 13, 2009, 1:02 PM   #23
Senior Member
 
penolta's Avatar
 
Join Date: Apr 2007
Location: California USA
Posts: 5,206
Default

Tamron has come out with an 18-270 which may replace their 18-250, although it is more expensive. They have an 18-200 and they may have felt they were too close. If the Pentax lens is made by Tamron, it may be replaced as well.
penolta is offline   Reply With Quote
Old Apr 13, 2009, 9:16 PM   #24
Senior Member
 
penolta's Avatar
 
Join Date: Apr 2007
Location: California USA
Posts: 5,206
Default

Patty, I just read on another forum that a K20 user had a Tamron lens (not the same one) that wouldn't focus properly until he updated to the latest (newly released) firmware version for the K20, and now it focuses fine! Have you updated your camera yet?
penolta is offline   Reply With Quote
Old Apr 14, 2009, 6:19 AM   #25
Senior Member
 
nhmom's Avatar
 
Join Date: Jun 2006
Location: Southern New Hampshire
Posts: 5,202
Default

penolta wrote:
Quote:
Patty, I just read on another forum that a K20 user had a Tamron lens (not the same one) that wouldn't focus properly until he updated to the latest (newly released) firmware version for the K20, and now it focuses fine! Have you updated your camera yet?
I hadn't yet. Specifically because of the problem I'd been having. Didn't want to add more variables into the mixture. Let me meet with Lou tonight and see how things work with his and then I'll update. I hope it's as simple as that. That would be great. I had been thinking it shouldn't make a difference since I have the same problem with my K100 (one of the first ones released, not the super).

There's hope still. Or, maybe it's just I don't know the trick to using it yet.

Patty
nhmom is offline   Reply With Quote
Old Apr 14, 2009, 6:04 PM   #26
Senior Member
 
bigdawg's Avatar
 
Join Date: Feb 2005
Location: Thach Alabama
Posts: 14,981
Default

Patty it seems something mechanical is keeping you from obtaining infinity focus. This can be caused by the focus ring not being able to advance your inner lens sets to the distance required for infinity focus to happen. This is not most times from a dirty lens as that will affect close focus as well as infinity focus. The other thing that can happen (from my manual lens experience) is the lens elements have some how moved from their position in the lens. This happens most often when a lens is opened and not properly put back together. It can also happen without the user doing anything. Also if the lens is not mount firmly to the camera that can cause this to happen but I do not think this is your problem.

You have just cause for a lens return for your money and if that doesn't happen then a warranty claim should be used to have it fixed free of charge to you. Hope you can get the return as it is the less stressful of the 2.

Dawg
bigdawg is offline   Reply With Quote
Old Apr 14, 2009, 9:06 PM   #27
Senior Member
 
nhmom's Avatar
 
Join Date: Jun 2006
Location: Southern New Hampshire
Posts: 5,202
Default

Okay, good news and bad news. Good news is that I'm not going crazy! Lou has confirmed that it is definitely a problem with the lens and not me. Whewww! We tried it on his K100 and he had the same problems I had. I used his Tamron 18-250 on my camera and had absolutely no problems focusing on things 3 houses down from his house.

Bad news is, I need to take a drive into Boston tomorrow to return it. And, the worst news, I need to start looking for another lens I can afford before we go on vacation in a few weeks.

I want to try one more test with the updated firmware on the camera and it's too dark out right now to test. So, if I can get up early enough in the morning (and be alert enough) to do the update I'll see if that makes a difference. I'm doubting it since it doesn't work on my or Lou's K100, but you never know.

One thing I've discovered from this is that there is a minor difference between the Pentax 18-250 and the Tamron 18-250. The Tamron lens is a macro lens. So, since I'm starting the hunt again, I think I'll be looking for that one instead since I have the opportunity. Besides it has a six year warranty. Price will be a huge factor, though.

Anyway, thanks for everyone putting up with my posts all week. I appreciate all the help I've gotten with this issue. Especially Lou giving up his Tuesday night to do some testing with me.

Patty


nhmom is offline   Reply With Quote
Old Apr 15, 2009, 6:38 AM   #28
Senior Member
 
nhmom's Avatar
 
Join Date: Jun 2006
Location: Southern New Hampshire
Posts: 5,202
Default

Just to report, the firmware update ver 1.03 for the K20D made no difference.

Thanks again, Patty
nhmom is offline   Reply With Quote
Old Apr 15, 2009, 10:21 PM   #29
Senior Member
 
nhmom's Avatar
 
Join Date: Jun 2006
Location: Southern New Hampshire
Posts: 5,202
Default

Returned the lens tonight and got my cash back. No problems. He tried it out and saw what I was talking about.

So, if anyone hears of any good buys on the Tamron 18-250 (or Pentax, although the macro feature would be great to have in an all-in-one), I'm all ears. :-) The short while I had that lens it proved to be the perfect every day lens for me when I'm just going back and forth to work.

Patty
nhmom is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:01 PM.